You're in a chatroom with people and it's clear that one Person thinks they are DM'ing Intended Recipient.
The Person writes their frank assessment of *you* personally and your allies — including mostly nasty and mean stuff that's just bullshit but some of it has some level of truthiness to it.
What do you do?
(I had this situation today and I basically just froze in uncertainty of what to do until it was all over.)